It is proposed to continue to improve the methodology for the determination of peptide sequencing by gas chromatographic mass spectrometry. In parallel, it will be used to determine the structure of chicken osteocalcin a protein implicated in the uptake and transport of calcium in bone, and of macromomycin, a protein which exhibits antitumor activity. These two polypeptides are 57 and ca. 125 amino acids long, respectively. Secondly, it is planned to develop a strategy for the determination of the structure of much large proteins ( approximately 1000 amino acids in length) by a combination of this GCMS peptide sequencing method and the Maxam-Gilbert DNA sequencing procedure. As the first test case which will also be used to develop the strategy we plan to determine the structure of alanine-tRNA-synthetase.